Business Week has published an in-depth profile of Scott Forstall, Senior Vice President of iOS Software at Apple.

Described as what may be the 'best remaining proxy for the voice of Steve Jobs', Forstall, 42, heads iOS, the operating system which runs on mobile devices accounting for 70% of Apple revenue.

"He was as close to Steve as anybody at the company," says Andy Miller, who formerly headed iAd. "When he says stuff, people listen."

In many ways, Forstall is a mini-Steve. He's a hard-driving manager who obsesses over every detail. He has Jobs's knack for translating technical, feature-set jargon into plain English. He's known to have a taste for the Mercedes-Benz SL55 AMG, in silver, the same car Jobs drove, and even has a signature on-stage costume: black shoes, jeans, and a black zippered sweater. (He favors Reyn Spooner Hawaiian shirts for normal days at the office.)

Forstall is like Steve in one other important way: He can be, in what some of his co-workers might call an understatement, a polarizing figure. He's won the intense loyalty and allegiance of many of his underlings, and his engineers are among the hardest workers at the company. At the same time, according to several former Apple employees, a number of high-ranking executives have left the company because they found working with Forstall so difficult. That sentiment, it seems, has not been limited to fellow executives. One former member of the iOS team, a senior engineer, describes leaving Apple after growing tired of working with Forstall and hearing his common refrain: "Steve wouldn't like that."

Interestingly, Business Week notes that Forstall may have been somewhat responsible for the lost iPhone 4 prototype. Apparently, it was Forstall who persuaded Jobs to let dozens of his engineers to carry prototypes in order to better test its network performance and minimize dropped calls.